Imaging lens

• US 10,564,394 B2
• Filed: 11/02/2017
• Issued: 02/18/2020
• Est. Priority Date: 11/02/2016
• Status: Active Grant

• Current Assignee: Tokyo Visionary Optics Company Limited
• Original Assignee: Kantatsu Company Limited (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Sekine, Yukio
• Primary Examiner(s): King, George G
• Application Number:
  US15/801,507
• Publication Number:
  US 20180348480A1
• Time in Patent Office: 838 Days
• Field of Search: 359713, 359752
• CPC Class Codes: G02B 13/0045 having five or more lenses
• CPC Class Codes: G02B 13/04 Reversed telephoto objectives
• CPC Class Codes: G02B 13/06 Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces
• CPC Class Codes: G02B 13/18 with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration G02B13/002 takes precedence
• CPC Class Codes: G02B 27/0037 with diffracting elements G02B27/0056 takes precedence; holographic optical elements G02B5/32; zone systems G02B5/1876
• CPC Class Codes: G02B 9/62 having six components only
• CPC Class Codes: H04N 25/00 Circuitry of solid-state image sensors [SSIS]; Control thereof

Abstract

There is provided an imaging lens with high resolution which effectively achieves low-profileness while maintaining the wide field of view, and favorably corrects aberrations.

The imaging lens comprising a first lens having negative refractive power, a second lens having positive refractive power, a third lens, a fourth lens having positive refractive power, a fifth lens having negative refractive power as a double-sided aspheric lens, and a sixth lens as a double-sided aspheric lens, wherein the first lens has a concave surface facing the image side, and the aspheric surface on the image side of the sixth lens is formed as a concave surface near the optical axis and has at least one pole point at an off-axial point, and a below conditional expression (1) is satisfied:
ω≥45°  (1)
where

ω: a half field of view.

Claims

1. An imaging lens forming an image of an object on a solid-state image sensor, comprising in order from an object side to an image side,

a first lens having negative refractive power,

a second lens having positive refractive power and a biconvex shape,

a third lens,

a fourth lens having positive refractive power,

a fifth lens having negative refractive power and is a double-sided aspheric lens, and

a sixth lens that is a double-sided aspheric lens,

wherein the first lens has a concave surface facing the image side near an optical axis, and the sixth lens has a concave surface facing the image side near the optical axis and at least one pole point at an off-axial point on an image-side surface, and

below conditional expressions (1), (5), and (9) are satisfied:

ω

≥

45°

 

 

(1)

−

2.5<

f1/f<

−

1.0 

 

(5)

−

6.0<

f5/f<

−

1.5 

 

(9)

where

ω

;

a half field of view,

f1;

a focal length of the first lens,

f5;

a focal length of the fifth lens, and

f;

a focal length of the overall optical system.

2. The imaging lens according to claim 1, wherein a conditional expression below is satisfied:

0.1<

SAG L1R/r2<

0.6 

 

(2)

where

SAG L1R;

an amount of sag at the peripheral area of the effective diameter of an image-side surface of the first lens, and

r2;

a curvature radius of the image-side surface of the first lens.

3. The imaging lens according to claim 1, wherein a conditional expression below is satisfied:

0.5<

r2/f<

1.5 

 

(3)

where

r2;

the curvature radius of an image-side surface of the first lens.

4. The imaging lens according to claim 1, wherein the third lens has negative refractive power and a concave surface facing the image side near the optical axis.

5. The imaging lens according to claim 1, wherein the fourth lens has a convex surface facing the image side near the optical axis.

6. The imaging lens according to claim 1, wherein the sixth lens has negative refractive power and a convex surface facing the object side near the optical axis.

7. The imaging lens according to claim 1, wherein a conditional expression below is satisfied:

f2−

f4>

0 

 

(4)

where

f2;

a focal length of the second lens, and

f4;

a focal length of the fourth lens.

8. The imaging lens according to claim 1, wherein conditional expressions below are satisfied:

0.5<

f2/f<

1.5 

 

(6)

−

6.0<

f3/f<

−

1.5 

 

(7)

0.5<

f4/f<

1.5 

 

(8)

−

2.5<

f6/f<

−

1.0 

 

(10)

where

f2;

a focal length of the second lens,

f3;

a focal length of the third lens,

f4;

a focal length of the fourth lens, and

f6;

a focal length of the sixth lens.

9. The imaging lens according to claim 1, wherein a conditional expression below is satisfied:

1.0<

f456/f<

2.5 

 

(11)

where

f456;

a composite focal length of the fourth lens, the fifth lens and the sixth lens.

10. The imaging lens according to claim 1, wherein a conditional expression below is satisfied:

0.2<

t1/f<

0.6 

 

(12)

where

t1;

a distance along the optical axis between the first lens and the second lens.

11. The imaging lens according to claim 1, wherein a conditional expression below is satisfied:

0.5<

CA1/ih<

2.0 

 

(13)

where

CA1;

an effective diameter of an object-side surface of the first lens,

Ih;

a maximum image height.

12. The imaging lens according to claim 1, wherein conditional expressions below are satisfied:

0.05<

SAG L1F/CA1<

0.50 

 

(14)

0.05<

SAG L1R/CA2<

0.50 

 

(15)

where

SAG L1F;

an amount of sag at the peripheral area of the effective diameter of an object-side surface of the first lens,

SAG L1R;

an amount of sag at the peripheral area of the effective diameter of an image-side surface of the first lens,

CA1;

an effective diameter of the object-side surface of the first lens,

CA2;

an effective diameter of the image-side surface of the first lens.

13. An imaging lens forming an image of an object on a solid-state image sensor, comprising in order from an object side to an image side:

a first lens having negative refractive power;

a second lens having positive refractive power;

a third lens having a concave surface facing the image side near an optical axis;

a fourth lens having positive refractive power and a meniscus shape;

a fifth lens having negative refractive power and is a double-sided aspheric lens; and

a sixth lens that is a double-sided aspheric lens,

wherein the first lens has a concave surface facing the image side near the optical axis, and the sixth lens has a concave surface facing the image side near the optical axis and at least one pole point at an off-axial point on an image-side surface, and below conditional expressions (1) and (5) are satisfied;

ω

≥

45°

 

 

(1)

−

2.5<

f1/f<

−

1.0 

 

(5)

where

ω

;

a half field of view

f1;

a focal length of the first lens, and

f;

a focal length of the overall optical system.

14. The imaging lens according to claim 13, wherein conditional expressions below are satisfied:

0.5<

f2/f<

1.5 

 

(6)

−

6.0<

f3/f<

−

1.5 

 

(7)

0.5<

f4/f<

1.5 

 

(8)

−

6.0<

f5/f−

1.5 

 

(9)

−

2.5<

f6/f<

−

1.0 

 

(10)

where

f2;

a focal length of the second lens,

f3;

a focal length of the third lens,

f4;

a focal length of the fourth lens,

f5;

a focal length of the fifth lens, and

f6;

a focal length of the sixth lens.